Centralized Exchange (CEX)
In simple terms
A centralized exchange is like a bank for cryptocurrency—a company runs it and holds your money while you buy and sell crypto. You trust the company to keep your funds safe and execute your trades fairly.
Definition
An exchange operated by a company.
In depth
A centralized exchange (CEX) is a custodial platform operated by a licensed company that maintains order books and matches buy/sell orders between users. The exchange holds users' private keys and funds in escrow, acting as an intermediary that facilitates price discovery through its matching engine. CEXs typically employ KYC (Know Your Customer) verification, fiat on/off-ramps via traditional banking rails, and maintain custody of assets—introducing counterparty risk but enabling faster order execution and better liquidity than peer-to-peer alternatives.
How does Centralized Exchange (CEX) work?
A customer opens an account with a company, which in most jurisdictions verifies identity first. Funding happens by bank transfer or by sending crypto to a deposit address the exchange controls. From that point the balance is a line in the exchange's own database, and the exchange holds the private keys. Trades are matched inside its engine, so they are fast and cheap because no blockchain transaction happens per trade. Only a withdrawal creates an on-chain transfer, moving coins to a wallet whose keys the customer controls. Until then, what is owned is a claim on the company.
An example
Someone transfers $1,000 from a bank account and buys $500 of an asset priced, illustratively, at $50 a unit. That is 10 units, less a 0.2 percent taker fee of $1, so about 9.98 units are credited. Those units are a database entry at the exchange until they are withdrawn on-chain, which costs a separate network fee and is the point at which custody actually changes.
Figures are illustrative only.
What beginners get wrong
- An exchange balance is not self-custody. The keys belong to the platform, so the account holder owns a claim rather than the asset itself.
- Skipping two-factor authentication, or relying on SMS codes that can be redirected through a SIM-swap attack, is behind a large share of account takeovers.
- Proof-of-reserves pages show assets without necessarily showing liabilities, so on their own they do not demonstrate that a platform is solvent.
- Matching only the ticker symbol during a withdrawal ignores the network selector, and sending on the wrong chain usually means the funds cannot be retrieved.
Related terms
Part of
How do you buy cryptocurrency safely? — the subject page for buying crypto, with all 15 of its definitions in one place.
Educational only — not financial advice.